FIXME: なにをするもの?
いろいろあるので、わかったことは随時追加。
命令定義
(define_insn "*movdi_64bit"
[(set (match_operand:DI 0 "nonimmediate_operand" "=r,r,r, m, *f,*f,*r,*f,*m")
(match_operand:DI 1 "move_operand" " r,T,m,rJ,*r*J,*m,*f,*f,*f"))]
★1 "TARGET_64BIT
★1 && (register_operand (operands[0], DImode)
★1 || reg_or_0_operand (operands[1], DImode))"
{ return riscv_output_move (operands[0], operands[1]); }
[(set_attr "move_type" "move,const,load,store,mtc,fpload,mfc,fmove,fpstore")
(set_attr "mode" "DI")])